In Ethernet MAC protocol we have preamble of 7 octets , which consist series of 1's and 0's so is there any specific reason behind this kind of pattern ?

 

In Ethernet MAC protocol we have preamble of 7 octets , which consist series of 1's and 0's so is there any specific reason behind this kind of pattern ?

Yes. Depending on the coding mechanism used for physical signaling, the preamble is used to establish bit synchronization at the beginning of a frame. In particular it is not required for all 56 bits of the Ethernet preamble to be correctly received. It is only required that enough of the preamble be received to allow for the recognition of the SFD (Start Frame Delimiter). Having established bit synchronization, the SFD establishes byte synchronization for the remainder of the frame.

10Base-T Ethernet uses Manchester encoding because it is self clocking. That is the reason for the alternating series of 1's and zero's.

https://en.wikipedia.org/wiki/Manchester_code